First results of a cosmic-ray electron and positron spectrum from 10 GeV to 3 TeV is presented based upon observations with the CALET instrument on the International Space Station starting in October, 2015. Nearly a half million electron and positron events are included in the analysis. CALET is an all-calorimetric instrument with total vertical thickness of 30 X0 and a fine imaging capability designed to achieve a large proton rejection and excellent energy resolution well into the TeV energy region. The observed energy spectrum over 30 GeV can be fit with a single power law with a spectral index of -3.152±0.016 (stat+syst). Possible structure observed above 100 GeV requires further investigation with increased statistics and refined data analysis.
Publication Source (Journal or Book title)
Physical Review Letters
Adriani, O., Akaike, Y., Asano, K., Asaoka, Y., Bagliesi, M., Bigongiari, G., Binns, W., Bonechi, S., Bongi, M., Brogi, P., Buckley, J., Cannady, N., Castellini, G., Checchia, C., Cherry, M., Collazuol, G., Di Felice, V., Ebisawa, K., Fuke, H., Guzik, T., Hams, T., Hareyama, M., Hasebe, N., Hibino, K., Ichimura, M., Ioka, K., Ishizaki, W., Israel, M., Javaid, A., Kasahara, K., Kataoka, J., Kataoka, R., & Katayose, Y. (2017). Energy Spectrum of Cosmic-Ray Electron and Positron from 10 GeV to 3 TeV Observed with the Calorimetric Electron Telescope on the International Space Station. Physical Review Letters, 119 (18) https://doi.org/10.1103/PhysRevLett.119.181101